In a wireless communication system, a user equipment (UE) may receive data and/or various control information from a base station (BS) through a downlink (DL) and transmit data and/or various control information to the BS through an uplink (UL). In order to communicate with the BS, the UE needs to establish synchronization with the BS. To this end, a UE, which is turned on from a power-off state or newly enters a cell which is a geographic region served by a BS, performs initial cell search accompanying operation such as synchronization establishment with the BS. Upon completion of initial cell search, the UE may receive data and/or control information through a physical downlink channel and transmit data and/or control information through a physical uplink channel.
Due to various reasons including cell search, maintenance of time synchronization after synchronization between a UE and a BS, and correction of a frequency offset, a wireless communication system discussed up to now defines transmission/reception of various mandatory signals on designated radio resources.
The types and number of these mandatory signals have increased with the advance of the standard of the wireless communication system. Since signals other than the mandatory signals cannot be allocated to radio resources to which the mandatory signals are allocated, the mandatory signals increasing in accordance with the advance of the wireless communication system hinder the degree of freedom of scheduling of the wireless communication system and also restricts introduction of more efficient communication technology for the wireless communication system.